HAPLN1-PTR1 induces chemotactic and chemokinetic migration in MM cells. (A) Microscopic images of RPMI8226 cells on transwell membranes that had migrated from the upper chamber to the lower chamber containing MBP or MBP-PTR1 at 100 nM or SDF-1 at 30 nM after 16 hours. (B) Graphs depicting percentage migration of RPMI8226 and MM.1S MM cells treated as in panel A with MBP control being set as 100%. (C) Graphs depicting percentage migration of CD138⁺ primary MM cells isolated from 6 patients in response to MBP, MBP-PTR1, or SDF-1 with MBP control being set as 100%. (D) Migration of RPMI8226 cells in response to indicated MBP-PTR1 concentrations in the upper and lower chambers were quantified with the control (0 nM) set at 100%. (E) Individual cell track trajectories of 3 groups in time-lapse μ-slide migration assay using RPMI8226 cells recorded for 16 hours are shown: positive gradient (−/+; 30 nM MBP/MBP-PTR1), negative control (−/−; 30 nM MBP/MBP), and no gradient (+/+; 30 nM MBP-PTR1/MBP-PTR1). The y-axis is parallel to the chemotactic gradient in which cell trajectory going up along the y-axis is the migration toward the MBP-PTR1 in the positive-gradient group. (F) Graphs showing the comparison of averaged FMI^II and FMI^⊥ for each group from panel E. (G) Graph showing the comparison of the cell speed from panel E. All experiments were independently repeated 3 times for panel D and 4 times for panels B,E-G. Data are expressed as means ± standard error of the mean (SEM). ∗P < .05; ∗∗P < .01; ns, not significant.